[Inflammatory mediator and organ dysfunction syndrome].

Abstract

Inflammatory mediators include endotoxin (ETX), cytokines (interleukins [ILs], tumor necrosis factors [TNFs], and interferons), eicosanoids (prostaglandins and thromboxanes), reactive oxygen species (O2-, NO, and ONOO-), complements (C3 and C4), and stress hormones (catecholamine, cortisol, vasopressin, and growth hormone). These mediators work to maintain homeostasis under stressful conditions through a complex chain reaction or cascade that results in transient tissue damage known as the inflammatory response. The inflammatory response is decreased by a negative feedback system, which consists not only of the self-inhibitory action of ETX, TNF-alpha, IL-1, and IL-8, but also of the production of antiinflammatory mediators such as IL-4, -10, -11, and -13, TGF-beta, IL-Ra, and sTNFR. If excessive stress or a second attack of stress results in a higher level of inflammation-producing mediators than of inflammation-inhibiting mediators, tissue destruction occurs due to activation and infiltration of inflammatory cells or necrosis due to endothelial injury is seen, followed by disruption of homeostasis, organ dysfunction, and organ failure (multiple organ dysfunction syndrome [MODS] or multiple organ failure [MOF] induced by SIRS). In experimental liver dysfunction after 95% hepatectomy, massive apoptosis of hepatocytes is induced by prolonged hypercytokinemia, ONOO- production, decreased mitochondrial membrane potential of hepatocytes, and decreased Bc12 levels. On the other hand, if the antiinflammatory response is greater than the inflammatory response (CARS) a compromised state and refractory infection are seen, followed by progressive, irreversible organ dysfunction (MODS or MOF induced by CARS).